Recently, a magnetic random access memory (MRAM) using a spin-polarized electric current has been proposed. This MRAM uses a perpendicular-magnetization magnetic tunnel junction (MTJ) element.
In the perpendicular-magnetization MTJ element, a leakage magnetic field from a reference layer sometimes shifts the hysteresis of a storage layer, and this makes it impossible to write information in a zero-field state. To zero the shift magnetic field, therefore, a shift adjustment layer is formed in the MTJ element. However, the leakage magnetic field from the reference layer increases as the degree of micropatterning increases. This makes it necessary to increase the leakage magnetic field from the shift adjustment layer as micropatterning advances. To increase the leakage magnetic field from the shift adjustment layer, it is necessary to increase the saturation magnetization of the shift adjustment layer, or increase the film thickness of the shift adjustment layer. However, the perpendicularity of the shift adjustment layer becomes difficult to hold if the saturation magnetization is increased, and a pillar shape becomes difficult to process if the film thickness is increased.